Question

Which of the following ions has the largest size?
A. ${{F}^{-}}$
B. $C{{s}^{+}}$
C. $A{{l}^{+3}}$
D. $O_{2}^{-}$

Answer 1

Hint: We know that the distance from the center of the nucleus of the atom to the boundary of the shells is known as the ionic radius. As the number of electrons are going to add to an atom in their valence atomic orbitals, the ionic radius of the atom increases.

Complete answer:
The distance from the center of the nucleus of the atom to the boundary of the shells is known as the ionic radius. The trend in ionic radius is as follows: The ionic radius decreases from left to right across the period. The ionic radius increases down the group. In the same way, as the number of electrons is removed from the atom, the atomic or ionic radius of the atom decreases since the same number of protons are pulling lesser electrons. In the periodic table the atomic radius increases as we move from top to bottom and decreases as we are moving from left to right. All these ions belong to the group of the periodic table. A positively charged ion is formed when electrons are removed from a neutral atom. A negatively charged ion is formed when electrons are added from a neutral atom.
In the periodic table, the elements are arranged in an increasing order of their atomic numbers. As we move from top to bottom in the periodic table, the ionic radius of elements keeps on increasing. This is because as one electron is removed from the valence shell of the atom, the effective nuclear charge on the valence shell decreases. Thus, ionic radius increases. As we move from top to bottom in the periodic table, the atomic number of the elements increases. $C{{s}^{+}}$ has the highest ionic radii as it is on the extreme right corner of the table. So, it is the highest in its period and highest in the group.

So, the correct answer is “Option B”.

Note:
Remember that the ionic radius is the radius of an ion. An ion can be positively or negatively charged. In a space lattice, the ionic radius may be a measure of the dimensions of the atom's ion. When formed, ionic atoms change in size with reference to their original atom.